Add retry logic for Docker build and push

[adamtheturtle]

The Docker build fetches packages from PyPI inside the container. Due to CDN propagation delays after a release, the build may fail if it hits a different CDN node than the one where the package was originally published.

This adds retry logic using nick-fields/retry@v3 with up to 5 attempts and a 10-minute timeout per attempt, matching the pattern used in https://github.com/adamtheturtle/doccmd/.

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Note

Introduces retry logic around the Docker image build/push in the release workflow to handle PyPI CDN propagation races.

• Replace docker/build-push-action@v6 with nick-fields/retry@v3 running docker buildx build --push for linux/amd64, linux/arm64, tagging ${{ steps.calver.outputs.release }} and latest, and passing VWS_CLI_VERSION as a build arg
• Configure retries: max_attempts: 5, timeout_minutes: 10; add comments explaining the PyPI race condition

^{Written by Cursor Bugbot for commit a7f74ce. This will update automatically on new commits. Configure here.}